• Earthquakes and Structures
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• v.18 no.2
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• pp.215-222
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• 2020

In this paper, slit steel rubber bearing is presented as an innovative seismic isolator device. In this type of isolator, slit steel damper is an energy dissipation device. Its advantages in comparison with that of the lead rubber bearing are its simplicity in manufacturing process and replacement of its yielding parts. Also, slit steel rubber bearing has the same ability to dissipate energy with smaller value of displacement. Using finite element method in ABAQUS software, a parametric study is done on the performance of this bearing. Three different kinds of isolator with three different values of strut width, 9, 12 and 15 mm, three values of thickness, 4, 6 and 8 mm and two steel types with different yield stress are assessed. Effects of these parameters on the performance characteristics of slit steel rubber bearing are studied. It is shown that by decreasing the thickness and strut width and by selecting the material with lower yield stress, values of effective stiffness, energy dissipation capacity and lateral force in the isolator reduce but equivalent viscous damping is not affected significantly. Thus, by choosing appropriate values for thickness, strut width and slit steel damper yield stress, an isolator with the desired behavior can be achieved. Finally, the performance of an 8-storey frame with the proposed isolator is compared with the same frame equipped with LRB. Results show that SSRB is successful in base shear reduction of structure in a different way from LRB.

• Steel and Composite Structures
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• v.47 no.3
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• pp.423-436
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• 2023

In this research, we tested 10 simply supported concrete-encased composite columns under monotonic eccentric loads and investigated their shear behaviour. The specimens tested were two reinforced concrete specimens, three steel-reinforced concrete (SRC) specimens with an H-shaped steel section (also called a beam section), and five SRC specimens with a cruciform-shaped steel section (also called a column section). The experimental variables included the transverse steel shape's depth and the longitudinal steel flange's width. Experimental observations indicated the following. (1) The ultimate load-carrying capacity was controlled by web compression failure, defined as a situation where the concrete within the diagonal strut's upper end was crushed. (2) The composite effect was strong before the crushing of the concrete outside the steel shape. (3) We adjusted the softened strut-and-tie SRC (SST-SRC) model to yield more accurate strength predictions than those obtained using the strength superposition method. (4) The MSST-SRC model can more reasonably predict shear strength at an initial concrete softening load point. The rationality of the MSST-SRC model was inferred by experimentally observing shear behaviour, including concrete crushing and the point of sharp variation in the shear strain.

• Steel and Composite Structures
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• v.44 no.5
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• pp.677-684
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• 2022

This paper reports experimental investigation on shear behavior of steel reinforced concrete (SRC) shallow floor beam, where the steel shape is embedded in concrete and the high strength bolts are used to transfer the shear force along the interface between the steel shape and concrete. Six specimens were conducted aiming to provide information on shear performance and explore the shear bearing capacity of SRC shallow floor beams. The effects of the height of concrete slab, the size and the type of the steel section on shear performance of beams were also analyzed in the test. Based on the strut-and-tie model, the shear strength of the SRC shallow floor beam was proposed. Experimental results showed that composite shallow floor beam exhibited satisfactory composite behavior and all of the specimen failed in shear failure. The shear bearing capacity increased with the increasing of height of concrete slab and the size of steel shape, and the bearing capacities of beam specimens with castellated steel shape was slightly lower than those of specimens with H-shaped steel section. Furthermore, the calculations for evaluating the shear bearing capacity of SRC shallow floor beam were verified to be reasonable.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.75-83
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• 2018

In study, Structural stability was considered when applying the high strength strut method with improved general strut method. considered whether there is sufficient stiffness to so as not buckling to the maximum hypothetical earth pressure. also structure stability of the strut component was reviewed. The high strength strut method is a technique used in place of the general strut method. high strength prefabricated Strut method is a technique that has bolt holes drilled in the upper flange at regular intervals. As a result of the buckling analysis, it was considered that the safety factor increased by about 5 %. also Since the stress generated is below the allowable stress, it is judged that structural stability of the strut is ensured. In particular, the safety factor of axial compressive stress increases about 16 % with use of high strength steel when applying the high strength prefabricated strut method. the high strength strut method is construction method may shorten the construction period and there is no expense to purchase additional materials.

• Computers and Concrete
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• v.16 no.3
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• pp.357-380
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• 2015

In this study, a simple indeterminate strut-tie model which reflects complicated characteristics of the ultimate structural behavior of continuous reinforced concrete deep beams was proposed. In addition, the load distribution ratio, defined as the fraction of applied load transferred by a vertical tie of truss load transfer mechanism, was proposed to help structural designers perform the analysis and design of continuous reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie was introduced to ensure the ductile shear failure of reinforced concrete deep beams, and the primary design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete were reflected upon. To verify the appropriateness of the present study, the ultimate strength of 58 continuous reinforced concrete deep beams tested to shear failure was evaluated by the ACI 318M-11's strut-tie model approach associated with the presented indeterminate strut-tie model and load distribution ratio. The ultimate strength of the continuous deep beams was also estimated by the experimental shear equations, conventional design codes that were based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the proposed strut-tie model and load distribution ratio was examined through the comparison of the strength analysis results classified according to the primary design variables. The present study associated with the indeterminate strut-tie model and load distribution ratio evaluated the ultimate strength of the continuous deep beams fairly well compared with those by other approaches. In addition, the present approach reflected the effects of the primary design variables on the ultimate strength of the continuous deep beams consistently and reasonably. The present study may provide an opportunity to help structural designers conduct the rational and practical strut-tie model design of continuous deep beams.

• Steel and Composite Structures
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• v.21 no.5
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• pp.963-980
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• 2016

The jib system with middle strut is widely used to achieve the large arm length in the large scale tower crane and the deployability in the mobile construction crane. In this paper, an analytical solution for the out-of-plane buckling of the jib system with middle strut is proposed. To obtain the analytical expression of the buckling characteristic equation, the method of differential equation was adopted by establishing the bending and torsional differential equation of the jib system under the instability critical state. Compared with the numerical solutions of the finite element software ANSYS, the analytical results in this work agree well with them. Therefore, the correctness of the results in this work can be confirmed. Then the influences of the lateral stiffness of the cable fixed joint, the dip angle of the strut, the inertia moment of the strut, and the horizontal position of the cable fixed joint on the out-of-plane buckling behavior of the jib system were investigated.

• Advances in Computational Design
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• v.1 no.3
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• pp.253-264
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• 2016

Based on the variation of strain along the cross section, any region in a structural member can be classified into two regions namely, Bernoulli's region (B-region) and Disturbed region (D-region). Since the variation of strain along the cross section for a B-region is linear, well-developed theories are available for their analysis and design. On the other hand, the design of D-region is carried out based on thumb rules and past experience due to the presence of nonlinear strain distribution. Strut-and-Tie method is a novel approach that can be used for the analysis and design of both B-region as well as D-region with equal importance. The strut efficiency factor (${\beta}_s$) is needed for the design and analysis of concrete members using Strut and Tie method. In this paper, equations for finding ${\beta}_s$ for bottle shaped struts in concrete deep beams (a D-region) with and without steel fibres are developed. The effects of transverse reinforcement on ${\beta}_s$ are also considered. Numerical studies using commercially available finite element software along with limited amount of experimental studies were used to find ${\beta}_s$.

• Computers and Concrete
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• v.19 no.5
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• pp.589-597
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• 2017

Strut-and-tie modeling method, which evolved on truss-model approach, has generally been preferred for the design of complex reinforced concrete structures and structural elements that have critical shear behavior. Some structural members having disturbed regions require exceptional detailing for all support and loading conditions, such as the beam-column connections, deep beams, short columns or corbels. Considering the general expectation of exhibiting brittle behavior, corbels are somewhat dissimilar to other shear critical structures. In this study, reinforcement layout of a corbel model was determined by the participation of structural optimization and strut-and-tie modeling methods, and an experimental comparison was performed against a conventionally designed model.

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.602-609
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• 2001

A strut-and-tie model was proposed to predict the shear strength of RS beam which is a hybrid steel beam with reinforced concrete ends. The proposed model is capable of considering the concrete softening effects due to diagonal shear cracks at the embedded area of steel in concrete. It can predict tile failure strength of RS beam from the mathematical formulations which are based on equilibrium, compatibility, and the constitutive laws of cracked reinforced concrete. The previous experimental results of 15 RS beams were analyzed with the proposed model and the analytical results were also compared with formulas currently available. The comparison revealed that the proposed model can predict the strength of RS beam better than the others. The average ratio of experimental strengths to analytical results was 1.02 and the standard deviation was 0.126.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.975-981
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• 2017

Savings in weight using lightweight materials such as aluminum alloy can lead to increase fuel economy. However, compared to steel, aluminum alloys have a lower strength for an equivalent life cycle. To reduce the weight of automobiles, research is being performed on the fabrication of lighter and stronger torque struts without having to sacrifice the safety of automotive components. In this study, a weight reduction design process for torque struts is proposed that is based on varying von-Mises stress contours using an aluminum alloy (A356) having a tensile strength of 245 MPa, instead of STKM11A steels. The optimized design can reduce the weight of the original steel torque strut by over 42% and it can contribute to the design of light-weight components and to the safe design of torque struts.